According to the journal Frontiers In Neuroscience, around 80% of the world’s population is exposed to excessive or inappropriate use of artificial light outdoors, dubbed “light pollution”.

While the health risks of excessive light pollution can include sleep deprivation, fatigue, headaches, stress and anxiety, new research published in the journal has revealed that it could actually lead to Alzheimer’s Disease.

In the study, researchers used satellite-acquired data to determine nighttime light intensity in states, and compared that data with Alzheimer’s Disease prevalence in the same places, finding that a positive correlation was found in areas with the most light pollution in every year studied.

The study also indicated that nighttime light pollution had a stronger correlation to Alzheimer’s Disease risk than alcohol abuse, chronic kidney disease, depression, heart failure and obesity, but less of a link to the conditions of atrial fibrillation, diabetes, hyperlipidemia, hypertension and stroke.

This was especially true for those under the age of 65.

Robin Voigt-Zuwala, PhD, lead investigator for the study said: “Certain genes can influence early-onset Alzheimer’s, and these same genes may cause increased vulnerability to the effects of nighttime light exposure.

“Additionally, younger people are more likely to live in urban areas and have lifestyles that may increase exposure to light at night.”

The experts at the International Union for Conservation of Nature (IUCN) recommend the following for individuals and communities to protect against light pollution:

• Need: Use light only where needed. Consider how the use of light will impact the area, including wildlife interactions and habitats. Rather than permanent lights, use reflective paint or self-luminous markers for signs, curbs, and steps. Outdoor lighting should not be used for aesthetic purposes.
• Brightness: Use the least amount of light needed for the activity taking place. Be aware of surface conditions as some surfaces reflect a lot of light into the sky.
• Colour: Minimise blue and violet spectral components, i.e. use warm-white, yellow, or amber light. This aids night vision by all animals, including people.
• Shielding: Use shielding so that light does not spill beyond where it is needed. To reduce skyglow, do not use luminaires that project any light above the horizontal. Reduce glare by restricting beams to downward cones. This improves the ability of drivers and pedestrians to see into shadows.
• Timing: Use light only when needed. Turn lights off after use, or use active controls such as timers and motion detectors so that lights are on only when needed.
• Encourage neighbours to reduce their light pollution by observing these principles, especially to reduce glare and light trespass into your domain.